Functions of redoxins in plant development and stress response

Responsible Jean-Philippe REICHHELD (DR2 CNRS)

Modulation of plant development in response to stress is a key feature of adaptation of plants to environment conditions. Redox signaling pathways are involved in many aspects of these responses, detoxifying reactive oxygen species produced during stress responses or regulating developmental processes. Thiol redox signaling is an ideal candidate to link plant development to environmental sensing. Our group is studying redoxins, including thioredoxins (Trx) and glutaredoxins (Grx), which are the two protein families able to reduce disulfide bridges in target proteins. Numerous proteins present cysteines moving reversibly from disulfide to dithiol. In some reductases, this allows the entry of the reducing power necessary for their activity. But in most cases, the reduction of the disulfide bridge induces a stable conformational change regulating the characteristics of the protein, thus being comparable to other post-translational modifications like phosphorylation/dephosphorylation. Proteins reduced by redoxins are implicated in diverse phenomena including basal metabolism, defence against oxidants or pathogens as well as the transcriptional regulation, cell proliferation and photosynthesis.

In plants, many redoxin genes have been identified as well as numerous target proteins, most of them being isolated as Trx targets by in vitro studies. A main challenge remains to find new functions of redoxins in vivo, and to assign a specific redoxin to the reduction of specific targets in vivo. As a major item, our group focuses its efforts to unravel the specific Redoxins/target relationships by developing genomic, biochemical and genetic strategies. The major goals are :

  • Assign new functions to cytosolic, mitochondrial and nuclear Trx and Grx. Key tools for this research is the isolation of a collection of knock-out mutants in discrete Trx, Grx and in their respective reducers (Trx reductases, glutathione, glutathione reductases). Phenotypic, biochemical and genomic analyses of these mutants have enable to discover new functions of redoxin in different key steps of plant development and stress response: root and shoot meristematic development, hormone signaling (auxin and gibberellin), seed development, pollen fertility, oxidative stress response and iron-sulfur cluster formation. Importantly, genetic and biochemical studies have also highlighted several crosstalk between Trx and Grx reduction systems occurring in Arabidopsis. Deciphering key steps of these regulations will be a major challenge for future researches.
  • Find new target proteins regulated by redoxins involved in developmental and stress response pathways. Particular interest is focused on transcription factors involved in meristematic functions, hormone biosynthesis enzymes and transporters. This research combines bioinformatic, biochemical reduction tests and protein interaction approaches. A specific trx1 trx2 yeast two-hybrid strain in which both cytosolic endogenous TRX1 and TRX2 are non functional is a powerful tool allowing us to analyse specificity redoxin-target interactions.
  • equipe reichheld

    Team :

    JPh Reichheld is the leader of a GDR program devoted to Plant Redoxins, a French consortium involving 14 collaborating teams. Our projects are currently supported by ANR programs, as well as by international collaborations.

BARIAT Laëtitia - Assistant Ingénieur CNRS

BELIN Christophe - Maître de conférences UPVD

REICHHELD Jean-Philippe - Directeur de recherche CNRS

RIONDET Christophe - Maître de conférences UPVD

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